- See Section 2.279.
- Response parameter is pseudo-acceleration for 5% damping.
- Select the period range of usable PSA values based on cut-off frequencies of the high-pass filters used to correct records.
- Develop an orientation-dependent ground-motion measure based on maximum resultant response and ratio between response of an (arbitrarily) oriented SDOF system and maximum resultant response.
- Derive equations for the probability of exceedance for SDOF systems designed for different ways of combining the two horizontal components subjected to ground motions from an unknown direction.
- Investigate record-to-record variability of response and implied exceedance probability using a set of 108 records used by Boore et al. (1997) for 0.2 and 1.0s. Conclude that when using common methods for combining two horizontal components (such as geometric mean) that meaning of the return period of uniform hazard spectra is not clear because the major and minor axes of shaking are unknown before an event.
- Investigate SA resolved for different directions normalized by SA along the major axis for all selected records. Conclude that knowing SA along the major axis and the normalized SA for different direction completely defines the response in any direction. Derive empirical equation for the normalized SA w.r.t. angle and its probability distribution.
- Only report coefficients for 0.2, 0.3, 1, 2 and 3s in article. Provide coefficients for other periods as electronic supplement.